RESEARCH OBJECTIVES: The long term objective of this research is to explain the mechanism of insulin action in the human body in order to contribute towards improvement of clinical treatment of diabetes. The specific objectives of the proposed study are to elucidate the mechanism by which the hormone stimulates the receptor in the plasma membrane and thereby activates phosphodiesterase, which is probably associated with the endoplasmic reticulum in fat cells. We plan to study the properties of the insulin receptor and the hormone-sensitive phosphodiesterase and try to delineate the mechanism by which the insulin signal is transmitted from the receptor to the enzyme.